Optical design of zero-power Hubble Space Telescope wave-front correctors for null testing

Area of Science:

• Optical Engineering
• Astronomy Instrumentation

Background:

• Hubble Space Telescope's second-generation Wide Field/Planetary Camera requires optical correction.
• Spherical aberration in the Optical Telescope Assembly (OTA) degrades image quality.

Purpose of the Study:

• To design a method for testing and verifying optical corrections for the Hubble Space Telescope.
• To develop a lens system capable of simulating the OTA's spherical aberration for instrument testing.

Main Methods:

• Introduction of undercorrected spherical aberration into the wavefront.
• Design of a near-zero power doublet lens to generate a specific aberrated wavefront.
• Combination of the corrective instrument with the generated wavefront for testing.

Main Results:

• A method to test the aberration contribution's sign and magnitude was developed.
• A doublet lens design was created to mimic the OTA wavefront.
• The combined system is expected to produce a near-perfect wavefront and high-quality on-axis images.

Conclusions:

• The proposed lens system offers a simple and effective method for testing Hubble's optical instruments.
• This approach ensures the accurate compensation of spherical aberration for improved imaging.
• Designs are also presented for testing Optical Telescope Assembly simulators for other instruments.